Project Summary: Methamphetamine abuse has markedly increased since the 1990s and methamphetamine use among gay and bisexual men has been associated with cognitive deficits, risky sexual behavior, and an increased risk of contracting HIV/AIDS. Based on the current state of the research, it is unknown whether acute methamphetamine intoxication, or other factors such as multiple concurrent drug use, mediates these negative outcomes. The main goal of the current proposal is to address the gap in our knowledge by investigating cognitive performance and risky behavior following acute intranasal methamphetamine administration. We will conduct a series of double blind, placebo-controlled studies designed to measure the subjective and cognitive effects of intranasal methamphetamine (0, 12, 25, 50 mg) in current methamphetamine abusers. Using this study design, our first goal is to examine the effects methamphetamine on measures of risky behavior using two recently developed computerized tasks. The second goal of this proposal is to investigate potential mechanisms mediating risky behavior by correlating performance on a measure of metacognition of control with performance on tasks measuring risky behaviors. The third goal is to determine whether these measures of risky behavior and metacognition of control can predict subsequent methamphetamine-taking behavior under controlled laboratory conditions! Relevance: This proposed project is directly in line with the mission statement of NIDA's AIDS Research Program (ARP). Using a multidisciplinary and innovative approach, by combining aspects of cognitive psychology, decision-making, and neuropsychopharmacology, this project seeks to further our understanding of "the role of drug use and its related behaviors in the evolving dynamics of HIV/AIDS epidemiology." With this project we intend to examine risky behaviors that are associated with increased risk of HIV transmission. We will address a current gap in our knowledge by examining these behaviors following acute intranasal methamphetamine administration. This will further our understanding about the possible association between methamphetamine intoxication and the risk of HIV transmission.